Patent GB-933604-A (GB)
Title: Photographic roll-film camera with a film metering device
IPC: G03B1/66
Filed: 1960-01-12
Abstract: 933,604. Cameras. AGFA A.G. Jan. 12, 1960 [Jan. 30, 1959], No. 1138/60. Class 98 (1). A frame-counting device in a roll-film camera arrests the film-advancing mechanism after each advance of the film by one frame and is disengaged by operation of the shutter release lever which is spring-urged to an idle position where it obscures a film-number observation window, and which exposes the window in its operative position. As shown in Fig. 1, a spring-urged framecounting roller 14 is friction-driven by the film 10 and has a recess 15 for engagement, once in each revolution, of a tooth 16 of a three-armed latching lever 17, pivoted at 33 and spring- loaded at 18. A second arm of latch 17 has a tooth 22 engaging a ratchet-wheel 9 of a filmadvance mechanism while a third arm 29 bears against a lug 32 (see Fig. 3) on one arm 25 of a lever 24, pivoted at 27, a second arm 26 of the lever extending outside the camera housing for manual operation. Movement of this lever from the idle position (dotted in Fig. 3) against a tension spring 28 to the operating position, shown in full lines, causes the cam-shaped lug 32 of the lever to pivot latch 17 out of engagement with the ratchet-wheel 9 whilst still maintaining the engagement of tooth 16 in the recess 15 of the roller 14, and at the same time uncovering, by means of the aperture 30 in the pivoted lever, an inspection window 6 in the housing. It is thus possible, particularly when loading the film and winding it to the first exposure position, to maintain stationary the frame-counting roller 14 while winding the film to the correct position. During this time, the roller may be held out of contact with the film by means of lever 31 which is pushed upwards when lever 24 is in the operative position. The arm 29 of latch 17 may have a projection (not shown) which only allows pivoting of the lever 24 when tooth 16 engages recess 15. When lever 24 is inoperative (which will usually be the case unless it is required to observe the film number through window 6) latch 17, which has a stepped tooth 16, locks ratchet-wheel 9 together with roller 14 and a disc 19 of smaller radius than, and coaxial with, roller 14 and having a recess 23 of different depth from recess 15 (see Fig. 2); disc 19 is spring loaded for rotation relative to roller 14 within the limits of a pin-and-slot arrangement 21 so that on disengagement of tooth 16 with recess 15, disc 19 covers the recess and effectually blocks it. Such disengagement is caused by the shutter release as follows. On the same spindle 33 as latch 17 is mounted a bell-crank lever 34 urged by spring 36 against a lug 35 on latch 17 and having a recess 37 containing a shutter-release pin 38 with a conical bearing surface 39. Depression of the pin will pivot levers 34 and 17 in a clockwise direction, the tooth 16 leaving recess 15 which is then blocked by the snapping over of disc 19 so that tooth 16 cannot re-engage the recess and will ride on the periphery of the roller during film advance. The trailing edge of the recess in disc 19 is raised slightly with respect to the leading edge and engages tooth 16 after disc 19 has nearly completed one revolution. Roller 14 continues to rotate until recess 15 is aligned with recess 23 and latch 17 drops. During film-advance the lower edge of recess 37 in lever 34 blocks depression of pin 38 until, when one frame has been advanced, tooth 16 re-enters the recess 15. The film is advanced using handle 40 which also serves to re-tension the shutter release member 44 by means of cam 46.